1. Field of the Invention
The present invention is related to a method of manufacturing an organic electroluminescent (hereafter “electroluminescent” is abbreviated as EL) display element, an organic EL display element, and a portable information terminal equipped with an organic EL display element manufactured by such manufacturing method.
2. Description of the Prior Art
It is well known that organic EL display elements which utilize EL emitted light phenomenon is used in the display portions of various information terminals. A prior art method of manufacturing an organic EL display element is shown in FIGS. 1(a)˜1(d). FIGS. 1(a)˜1(d) are drawings for describing the manufacturing process of a prior art organic EL display element, wherein 51 represents a transparent substrate, 52 represents organic EL elements, 53 represents a seal cap, 54 represents a driving circuit, and 55 represents an organic EL display element.
First, a plurality of organic EL elements 52 is formed on top of a transparent substrate 51 (FIG. 1(a)). Although not shown in the drawings, the organic EL elements 52 are elements which have a transparent electrode, an organic EL layer and a metal electrode layer laminated onto the top of the transparent glass substrate 51. In order to process the organic EL elements 52, the transparent substrate 51 on which the plurality of organic EL elements 52 has been placed is cut to form individual organic EL elements (FIG. 1(b)). Because the organic EL layers of the organic EL elements are weakened by water, each of the organic EL elements 52 cut away into separate elements is sealed by a seal cap 53 (FIG. 1(c)) to prevent water in the air from flowing in. After sealing with the seal cap 53 has been carried out, a driving circuit 54 which drives the organic EL element is mounted by COG (Circuit on Glass) to the top of the seal cap to complete the organic EL display element 55 (FIG. 1(d)).
In this way, in the prior art, in the case where the driving circuit is mounted to the seal cap, after the organic EL element is sealed with the seal cap, because COG mounting is carried out, the rigidity of the seal cap needs to be increased. Consequently, the thickness of the seal cap becomes thick, whereby the thickness of the organic EL display element also becomes thick.
Further, because the organic EL elements 52 formed on top of the transparent substrate 51 are cut away to form individual elements, such elements need to be taken out from the vacuum chamber. In the process of covering the organic EL element 52 with the seal cap 53, because helium or the like is filled inside the seal cap, the organic EL element 52 needs to be returned again to an airproof chamber. Consequently, the manufacturing process becomes complicated.